The prior art has developed a wide variety of conveyors, some of which are useful for moving containers past an inspection station. However, none are available that can hold a bottle or other container vertically, horizontally transport it in a uniform vertical orientation with location repeatability, and provide free access to its bottom.
In one known system, illustrated in FIGS. 4 and 5 which depict this prior art, a pair of opposed belts 1 and 2 grip bottles 3 between tubular rubber cushions 4. Each of the rubber cushions is mounted on a plastic slide 5. The slides 5 are affixed to a chain drive 6. A flared base 7 on each of the slides guides the slide and the belt in which it is comprised around a rigid support track 8. The track 8 control the spacing of the belts. This type of transport suffers from two major problems: first, friction between the slides 5 and the track 8 causes wear and binding; and secondly, when the friction has caused wear, the belts can no longer hold the objects firmly enough to achieve consistent location, and vertical misalignment of the objects results from unpredictable alignment between the objects (shown as bottles 3) and the cushions 4. The alignment problem is illustrated.
When we attempted to correct the alignment problems by employing a flat belt which was guided over a smooth backing support, the belt rapidly began to wear and showed signs of failure. The use of rollers, instead of a smooth backing, to support the belt would not be an acceptable solution because the rollers would create high points in the belt. Those high points would cause vertical misalignment of the containers--either rotation from front to back or skewing from side to side with respect to the desired vertical axis.
There is a need for a method and apparatus capable of transporting a glass bottle or other container horizontally, while leaving the bottom free and maintaining a uniform vertical position. It is important to obtain consistent location relative to the centerline of an object. Precise centerline location is especially important when using optical cameras which, with computerized defect detection apparatus, compare the bottom of an object to a standard for identifying nonuniformities.